In a LTE-A (LTE-Advanced) system, a radio communication by CoMP (Coordinate Multi Point access) is discussed (for example, Non patent Documents 1, 2 below).
The CoMP is performed, for example, when a terminal is located in a region where it can communicate with a plurality of base stations (or sectors), by each base station transmitting data differing from the other by MIMO (Multiple Input Multiple Output) to the terminal.
On the other hand, in a radio communication system such as a LTE, the base station performs a scrambling process to transmission data (for example, Non-patent Documents 3, 4 below). For example, the base station adds transmission data b(0), . . . , b(Mbit-1) and scrambling codes c(i) and calculate a remainder (modulo) of “2” to perform scrambling. That is, the following formula is satisfied.{tilde over (b)}(i)=(b(i)+c(i))mod 2  [Expression 1]
Here, the scrambling code c(i) is a GOLD code of the length of “31”, and is obtained by the following generating polynomials.c(n)=(x1(n+NC)+x2(n+NC))mod 2  [Expression 2]x1(n+31)=(x1(n+3)+x1(n))mod 2  [Expression 3]x2(n+31)=(x2(n+3)+x2(n+2)+x2(n+1)+x2(n))mod 2  [Expression 4]
Here, the following formula also is satisfied.x1(0)=1, x1(n)=0, n=1,2, . . . ,30, NC=1600  [Expression 5]
Further, the initial value of the scrambling code c(i) is obtained by the following formula.cinit=nRNTI·214+└ns/2┘·29+NIDcell  [Expression 6]
That is, the initial value of the scrambling code c(i) is a value determined by the followings.
a terminal number:nRNTI (RNTI: Radio Network Temporary ID)  [Expression 7]
a (physical) cell (or, sector) number:NIDcell  [Expression 8]
and, a slot number:ns  [Expression 9]
The above numbers are used to determine the initial value of the scrambling code c(i).
Further, as one of conventional art of this type, for example, there is disclosed (for example, Patent Document 1 listed below) a controlling apparatus or the like, which has transmission assigning means which selects at least two transmission sectors for transmission to a mobile station according to a reception quality notified from the mobile station, and performs a transmission assignment to the mobile station, and transmission means which performs a transmission to the mobile station by using the same scrambling code from the transmission sector for identifying the sector.
Also, for example, there is disclosed (for example, Patent Document 2 listed below) a base station apparatus or the like, which has specific scramble generating means which generates scrambling codes specific to the base station, specific orthogonal sequence generating means which generates orthogonal sequences specific to the sector, and multiplication controlling unit which controls necessity of multiplication of the scrambling codes specific to the base station and the orthogonal sequences specific to the sector according to necessity of software combining for each physical channel.
Patent Document 1: Japanese Laid-open Patent Publication No. 2006-311475
Patent Document 2: Japanese Laid-open Patent Publication No. 2008-92379
Non patent Document 1: R1-084203
Non patent Document 2: 3GPP TS 36.210 V8.6.0
Non patent Document 3: 3GPP TS 36.211 V8.2.0
Non patent Document 4: R1-081229